Concern has been voiced that research on human stress has not been cumulative over the past fifteen years. Part of the problem is due to the importance and breadth of the field: stress is implicated in the onset or maintenance of many if not most psychological and chronic physical disorders. The problems with the advancement of knowledge in the field are related to the multilevelled nature of stress research and the absence of communication between levels (i.e., social, psychological, and physiological). More rapid progress in the field could be expected to result if a means of connecting research across levels were available. A focus on the mediating mechanisms through which the linkages across levels of analysis occur may serve to reconnect previously disjointed research effects. The proposed study will attempt to evaluate Schwartz' disregulation hypothesis, a process based model of the development of physical disorders, by assessing the relationship between subjective experience (self report stress/negative effect) and psychophysiology. Previous studies have found evidence for the disregulation of acute stress and life stress in tension headache, and it was suggested in these studies that acute stress disregulation has its origins in the linkage of this molecular level of analysis to more molar levels (such as in chronic or life stress). Twenty-five tension headache subjects, and 25 matched controls will be longitudinally assessed over a 6 month period for acute stress, daily hassles, life stress, headache symptoms and psychophysiological reactivity in response to laboratory stressors. Several variables hypothesized as causally implicated in the production of physiological disregulation will be evaluated for their influence on the process.